This invention relates to frequency conversion sytems and more particularly to a novel and useful time shared frequency conversion system wherein two or more information bearing signals are processed over a common frequency conversion signal path. In modulation and demodulation systems requiring an in-phase and a quadrature-phase channel, this invention provides an economy of components and automatic balancing of gain, frequency response and other electrical properties, by reason that only one set of components are required for the common time shared signal path. In superhetrodyne and direct conversion radio receiving systems, the first mixer must be of good quality in order to provide high quality performance. To receive a number of channels simultaneously, ordinarily requires a separate mixer, and band limited amplification system, such as an intermediate frequency (I.F.) amplifier, for each such channel. This invention provides that only one mixer and band limited amplification system may be employed, with the economy of reduced components, and reduced size. The savings may be utilized to incorporate a much higher quality mixer to the greatly improved performance of all channels.
A number of phase locked loop processes employ two channels, with a 90.degree. phase difference between channels. When the loop is in lock, one channel ordinarily carries phase error data, while the other, in-quadrature channel, carries amplitude data. In this invention only one channel is required for both. The Costas loop and asynchronous processes which include dual channels all find useful application of this invention. Asynchronous processes permit modulation and demodulation without locking. A beat note carrier will be found in each of two quadrature channels. The beat note will cancel by trigonometric relations, provided that each channel have identical gain. This invention provides the required identical gain and other desirable properties.